1. Field of the Invention
The present invention relates to a method of displaying a display mode using an on screen display(OSD) and, more particularly, to such a method of displaying information relating to the display mode as an OSD in response to the frequency of a picture signal which has been applied to a display monitor after amplification through a computer by users.
2. Discussion of Related Art
An example of such a conventional display monitor having the OSD function will now be described below with reference to the attached drawings.
FIG. 1 is a block diagram showing the internal circuit of a conventional display monitor.
As shown in FIG. 1, computer 100 is composed of a CPU 110 for processing a keyboard signal and thereby generating an output data, and a video card 120 for processing the data received from the CPU 110 into RGB picture signals and further generating horizontal and vertical synchronizing signals H/V-SYNC which are to synchronize the RGB picture signals.
Display monitor 200 receives the RGE picture signals and the horizontal and vertical synchronizing signals H/V-SYNC sent from the video card 120 in the computer 100. The display monitor 200 is composed of a microcomputer 210 receptive to the horizontal and vertical synchronizing signals H/V-SYNC, and discriminating a resolution; a control key section 220 for generating a screen control signal; a horizontal and vertical output circuit section 230 receptive to the screen control signal and a reference oscillating signal generated from the microcomputer 210, and synchronizing a raster; a video circuit section 240 for processing the RGB picture signals received from the video card 120 through amplification and displaying them; and a power supplying circuit section 250 for supplying a driving power to the microcomputer 210, the horizontal and vertical output circuit section 230, and the video circuit section 240.
Following is a detailed description of the respective blocks in the display monitor 200 of the construction.
Microcomputer 210 which stores all sorts of screen control data is receptive to the horizontal and vertical synchronizing signals H/V-SYNC sent from the video card 120, and generates an image adjusting signal and a reference oscillating signal in response to the screen control signal applied from the control key section 220.
Receiving the image adjusting signal and the reference oscillating signal from the microcomputer 210, a horizontal and vertical oscillating signal processor 231 supplies a vertical pulse to a vertical drive circuit 232. The vertical pulse is to control the switching rate of a sawtooth wave generating circuit in response to the horizontal and vertical synchronizing signals H/V-SYNC received from the video card 120.
As regards vertical drive circuit 232 receptive to the vertical pulse, most widely used are two types of them; one-stage vertical amplification type and emitter follower type. The emitter follower type vertical drive circuit has the base of the transistor therein used as an input with the emitter as an output. Hence, the vertical drive circuit 232 normally performs an operation for the improvement of linear characteristic not of the gain.
The vertical drive circuit 232, after amplification, supplies a drive current to a vertical output circuit 233, which will apply a sawtooth current corresponding to the vertical synchronizing pulse flowing through a V-DY, determining a vertical scanning period depending on the sawtooth current. In addition, a horizontal drive circuit 234 receives a horizontal oscillating signal from the horizontal and vertical oscillating processor 231, and accordingly, supplies a drive current high enough to switch the horizontal output circuit 235.
Upon receipt of the drive current from the horizontal drive circuit 234, the horizontal output circuit 235 will generate a sawtooth current to the H-DY, determining a horizontal scanning period depending on the sawtooth current. Such a horizontal drive circuit 234 is divided into two classes; in-phase type whose output is ON with the drive terminal ON, and out-of-phase type wherein the output is OFF with the drive terminal ON.
High-voltage circuit 236 and FET (flyback Transformer) 237 generate a high voltage in order to supply a stable DC voltage to the anode terminal 244a of a CRT (Cathode Ray Tube) 244. Even when a collector pulse is very weak, high-voltage circuit 235 and PBT 237 can generate a high voltage by use of a harmonic wave due to inductance and distribution capacity. This high voltage is applied to the anode terminal 244a of the CRT 244, forming a high voltage across the anodic surface of the CRT 244.
Simultaneously, the video circuit section 240 has an OSD (On Screen Display) IC 241 receiving an OSD data generated during the screen control of the microcomputer 210 to generate an OSD gain signal. This OSD gain signal from the OSD IC 241 is sent to a video pre-amplifier 242.
Upon receipt the OSD gain signal from the OSD IC 241 and the RGB picture signals from the video card 120, the video pre-amplifier 242 amplifies the RGB picture signals to a limited voltage level via a low-voltage amplifier.
For example, a signal less than 1 V.sub.pp is converted to the voltage of 4 to 6 V.sub.pp through an amplification in the video pre-amplifier 242. This picture signal is further amplified to 40 and 60 V.sub.pp in a video output amplifier 243 and then sent to the cathode of the CRT 244 for displaying an image. The image which has been produced through the CRT 244 in response to the RGB picture signals and the OSD signal has its scanning period determined by the H-DY and V-DY and is visually displayed on the screen of CRT 244. The RGB picture signals or the OSD signal which are amplified by the vide output amplifier 243 will be displayed as an image with the luminance regulated by the high voltage formed across the anode surface of CRT 244.
Power supplying circuit section 250, which is to provide a driving voltage for displaying the RG8 picture signals on the screen of the display monitor, receives an AC (Alternative Current) through an AC input 251. The AC is-applied to a degaussing coil 252, which resumes the color blotted due to the influence of the earth magnetic field or external environment to the original distinct one.
For this, degaussing coil 252 disperses the magnetic field of a DC component formed across the shadow mask in CRT 244 while an AC is applied to the degaussing coil 252 momentarily for 2-8 seconds, and prevents the electron beams from being deflected unstably due to the magnetic field.
The AC is normally rectified into a DC through a rectifier 251 and transmitted to a switching transformer 254. The switching transformer 254 supplies all sorts of driving voltage required in the monitor 200 via a voltage regulator 255. At this stage, PWM (Pulse Width Modulation) IC 256 controls the switching operation of the switching transformer 254, stabilizing the output voltage of the transformer.
Microcomputer 210 is under the control of a DPMS (Display Power Management Signaling) mode to economize power consumed in the display monitor 200. In this respect, the microcomputer 210 sets up a power-off mode and a suspend mode depending on the presence of horizontal and vertical synchronizing signals H/V-SNC, and accordingly saves the power in the display monitor 200.
If the user adjusts a screen or wants to have information about the display mode of the display monitor which is in a current use, he has to choose the OSD function through the control key section 220 as programmed in the microcomputer 210.
Upon the user's pressing a button for the OSD function, the microcomputer 210 serves the OSD function in response to a key signal through the OSD IC 241. In this case, the microcomputer 210 sends an OSD data already stored therein to the OSD IC 241, which processes the OSD data to generate an OSD gain signal to the video pre-amplifier 242 and the video output amplifier 243. The OSD gain signal is then displayed on the screen of the CRT 244 after amplification via those amplifiers 242 and 243.
Under the OSD signal, the CRT 244 displays menus relating to the OSD function on the screen. The user may choose one menu by using the control key section 220 to have information about display monitor, screen adjustment, display mode, horizontal and vertical frequencies, and the like.
The user who needs to have information with regard to the display mode with the OSD function programmed in the conventional display monitor, however, occasionally encounters several troubles in that it is hard to explore information in another display mode changed or to know whether the current display mode displayed on the monitor is in the optimum state or not.